1. Field of the Invention
The present invention relates to a method of adjusting a rangefinder apparatus for measuring the distance to an object to be measured; and, in particular, to a method of adjusting an active type rangefinder apparatus suitably used in a camera or the like.
2. Related Background Art
In active type rangefinder apparatus used in cameras and the like, an infrared light-emitting diode (IRED) projects a luminous flux toward an object to be measured, the reflected light of thus projected luminous flux is received by a position sensitive detector (PSD), a signal outputted from the PSD is arithmetically processed by a signal processing circuit and an arithmetic circuit and then is outputted as distance information, and the distance to the object is detected by a CPU. In general, since errors may occur when the distance is measured upon a single light-projecting operation, light is projected a plurality of times so as to obtain a plurality of distance information items, and an integrating capacitor of an integrating circuit is discharged at predetermined intervals according to the plurality of distance information items, so as to effect integration (first integration), thereby averaging the plurality of distance information items. Thereafter, this integrating capacitor is charged at a constant rate (second integration), the time (second integration time) required for regaining the original voltage is determined as the result of integration, and a distance signal for causing a taking lens to effect a focusing action is computed in conformity with a predetermined converting expression according to the second integration time. This converting expression is determined for each camera before its shipment from a factory.